He definitely can use the help. As he's closing in to finish off the weakened demon, there's another one creeping out of the rift. All the more reason to get the thing closed, already. "Deal with the demon, I'll close that rift!" Now he's getting in a good spot to, once he takes care of the one he's facing. He stabs forward, slicing it apart. Then he shifts his focus toward the rift, as it it's an enemy as well.